The present invention relates generally to medical devices and methods, and more particularly to catheter devices and methods that are useable to form channels (e.g., penetration tracts) between vessels such as arteries and veins as well as between vessels and other anatomical structures, in furtherance of a therapeutic purpose such as bypassing an arterial blockage, delivering therapuetic agents, or performing other interventional procedures.
Applicant has invented several new interventional procedures wherein channels (e.g., bloodflow passageway(s)) are formed between blood vessels, and between blood vessels and other target structures, using transluminally advanceable catheters. These new procedures include novel percutaneous, transluminal techniques for bypassing obstructions in coronary or peripheral arteries through the use of the adjacent vein(s) as in situ bypass conduit(s), and other means of revascularizing oxygen starved tissues or delivering therapuetic substances to vessels, tissue and other organs. These procedures are fully described in U.S. Pat. No. 5,830,222 and in U.S. patent application Ser. Nos. 08/730,496, 09/048,147 and 09/048,147. Some of these procedures may be performed by a venous approach, such as vein-to-artery wherein a tissue penetrating catheter is inserted into a vein and the desired arterio-venous passageway is initially formed by passing a tissue penetrating element (e.g., a flow of energy or an elongate penetration member) from a catheter, through the wall of the vein in which the catheter is positioned, and into the lumen of an adjacent artery. Alternatively, some of these procedures may be performed by an artery-to-vein approach wherein the catheter is inserted into an artery and the desired arterio-venous passageway is initially formed by passing a tissue penetrating element (e.g., a flow of energy or elongate penetration member) from the catheter, through the wall of the artery in which the catheter is positioned, and into the lumen of an adjacent vein. Both approaches have been previously described in U.S. patent application Ser. No. 08/730,327. In addition, it may be advantageous to direct a penetrating element directly into other anatomical structures such as the myocardium, pericardium, chamber of the heart or other organs as described in U.S. patent application Ser. No. 09/048,147.
Different considerations and limitations may apply, depending upon which of these approaches (the vein-to-artery approach, the xe2x80x9cartery-to-veinxe2x80x9d approach, or vessel to other anatomical structure) is being used or, more generally, the size and contour of the blood vessel lumen in which the operative catheters are to be placed, and the distance and/or angle between the vessels or other target. This is due in part to the fact that, in the heart as well as in other areas of the body, adjacent arteries and veins may be of significantly different diameter and significantly different dilatory capability. In addition, depending on the procedure to be performed, for example, such as the desired angle of channel creation between blood vessels, one approach may be preferred over the other, to promote, among other things, blood flow channels that encourage non-turbulent blood flow. Also, the consequences associated with causing temporary complete obstruction of a vein may be significantly less than the consequences of causing temporary complete obstruction of an artery. Thus, it is desirable to devise tissue penetrating catheters of the above-described type that are sized, configured and/or equipped differently for use in blood vessels of different sizes, shapes and in connection with different types of pathology.
Moreover, it is desirable for tissue penetrating catheters of the abovedescribed type to be constructed and equipped for precise aiming and control of the tissue penetrating element as the tissue penetrating element passes from the catheter, through at least the wall of the blood vessel in which the catheter is located, and to the target location. Such aiming and control of the tissue penetrating element ensures that it will create the desired penetration tract at the intended location with minimal or no damage to surrounding tissues or other structures.
The present invention provides methods and apparatus for performing the percutaneous in situ coronary arterio-venous bypass procedures generally described in U.S. Pat. No. 5,830,222 and U.S. patent application Ser. No. 08/730,327, and other procedures requiring the use of accurately placed catheter elements.
A. Devices and System:
In accordance with the invention, there is provided a system for forming an initial penetration tract from the lumen of a blood vessel in which the catheter is positioned to a target location (such as another blood vessel, organ or myocardial tissue). This system generally comprises:
a) a coronary sinus guide catheter which is insertable within the venous system of the body and into the coronary sinus of the heart;
b) a tissue penetrating catheter which is advanceable to a position within a coronary vein, such tissue-penetrating catheter comprising i) a flexible catheter body, ii) a tissue penetrating element (e.g., a needle member, electrode or flow of energy) which is passable from the catheter body, through the wall of the coronary vein in which the catheter body is positioned and into the lumen of an adjacent coronary artery, or other targeted structure, iii) an imaging lumen through which an imaging catheter (e.g., an intravascular ultrasound imaging (IVUS) catheter) may be passed; and,
c) a separate imaging catheter (e.g., an intravascular ultrasound (IVUS) catheter) that is advanceable through the imaging lumen of the tissue-penetrating catheter.
In addition to components a-c above, this catheter system may include a subselective sheath and introducer. The subselective sheath comprises a flexible tubular sheath that has a proximal end, a distal end and a lumen extending therethrough. The introducer is insertable through the lumen of the sheath and has a tapered, non-traumatizing distal portion that protrudes out of and beyond the distal end of the sheath as well as a guidewire lumen extending longitudinally therethrough. The tapered, non-traumatic distal portion of the introducer serves to dilate the blood vessel lumens or openings through which the sheath is inserted, thereby facilitating advancement and positioning of the sheath at a desired location within the body. After the sheath has been advanced to its desired position within the body, the introducer is extracted and various channel modifying catheters, connector delivery catheters and/or blocker delivery catheters may be advanced through the subselective sheath.
The coronary sinus guide catheter may incorporate a hemostatic valve to prevent backflow or leakage of blood from the proximal end thereof. Also, the coronary sinus guide catheter may include an introducer that is initially insertable through the guide catheter lumen. This introducer has a tapered, non-traumatizing distal portion that protrudes out of and beyond the distal end of the guide catheter, and a guidewire lumen extending longitudinally therethrough. The tapered, non-traumatizing distal portion of the introducer served to dilate the blood vessel lumens through which the guide catheter is inserted, thereby facilitating advancement and positioning of the coronary sinus guide catheter within the coronary venous sinus.
The tissue-penetrating catheter may incorporate one or more of the following elements to facilitate precise aiming and control of the tissue-penetration element and the formation of the passageway at the desired location:
a) Orientation Structure: An orientation structure may be positioned or formed on the distal end of the tissue penetrating catheter. This orientation structure has i) a hollow cavity or space formed therewithin in alignment with the catheter""s imaging lumen and ii) a marker member positioned in direct alignment with the opening in the catheter through which the tissue penetrating element emerges (or otherwise in some known spacial relationship to the path that will be followed by the tissue penetrating element as it passes from the tissue penetrating catheter). The separate imaging catheter may be advanced through the tissue penetrating catheter""s imaging lumen and into the receiving space of the orientation structure. Thereafter, the imaging catheter is useable to image the target location as well as the marker. The image of the marker provides a path indication that is indicative of the path that will be followed by the tissue penetrating element as it passes from the tissue penetrating catheter. The operator may then adjust the rotational orientation of the tissue penetrating catheter as necessary to cause the path indication to be aligned with or aimed at the target location, thereby indicating that when the tissue penetrating member is subsequently passed from the catheter body, it will advance into the target location and not to some other location. In this manner the imaging lumen, separate imaging catheter and orientation structure that are incorporated into the catheter system of this invention operate, in combination with each other, to facilitate precise rotational orientation of the tissue penetrating catheter and aiming of the tissue penetrating element before the tissue penetrating element is advanced, thereby ensuring that the tissue penetrating element will enter the desired target at the desired location. In particular, the orientation structure may comprise a plurality (e.g., three) of longitudinal struts, such longitudinal struts being disposed about a central space into which the IVUS catheter may be advanced. One of such longitudinal struts may be aligned or specifically positioned in relation to the path that will be followed by the tissue penetrating element as it passes from the catheter, thereby providing on the display of the image received from the IVUS catheter, an artifact of other indication delineating the path or direction in which the tissue penetrating element will pass. The tissue-penetrating catheter may then be selectively rotated to aim the tissue penetrating element into the lumen of the artery or other target anatomical structure into which it is intended to pass.
b) Soft Distal Tip Member: The catheter may incorporate a soft distal tip member that is formed or mounted on the distal end of the tissue-penetrating catheter (e.g., on the distal aspect of the above-described orientation structure). Such soft tip member is preferably formed of material which is soft enough to avoid trauma to the walls of the blood vessels through which the tissue-penetrating catheter is passed. A lumen may extend longitudinally through the soft tip member, to allow the operator to selectively advance the IVUS catheter or other device beyond the distal end of the tissue-penetrating catheter when it is desired to image blood vessels or other structures located distal to the then-current position of the tissue-penetrating catheter or perform other diagnostic functions with said IVUS catheter or other device.
c) Tissue Penetrating Member Stabilizer: In embodiments wherein the tissue penetrating element is a needle or other elongate member that is advanceable laterally from the catheter body, the tissue penetrating catheter may incorporate a stabilizer to prevent or deter the tissue penetrating member from rotating or deviating from a predetermined acceptable penetration zone (APZ) (hereinafter sometimes referred to as the xe2x80x9cstabilizerxe2x80x9d). As used herein, the term stabilizer shall mean any structural or functional attributes of the catheter and/or tissue penetrating member that deter or prevent the tissue penetrating member from rotating or otherwise deviating from its intended path of advancement within a predetermined acceptable penetration zone (APZ). Examples of such structural and/or functional attributes include but are not limited to; curved distal housing formed to mirror the curve or form of the tissue penetrating element, engagement projections or elements for frictional engagement between the tissue penetrating member and the catheter body, bushings or narrowed/reduced diameter regions of the tissue penetration member lumen that serve to constrain the tissue penetrating member preventing side-to side play or movement thereof, permanent magnets or electromagnets that create a magnetic field that prevents or deters lateral or rotational movement of the tissue penetrating member, etc. More specifically, for example, this stabilizer may comprise one or more of the following:
i) a curved needle housing which mates (i.e. has the same direction of curvature) with a preformed curvature formed in the needle. This mating of the curvatures of the needle and needle housing serves to deter unwanted rotation and resultant lateral deviation (flopping or wagging) of the portion of the needle which extends out of the catheter body;
ii) frictionally engaged surfaces formed on the needle member and surrounding catheter body (e.g., the wall of the lumen in which the needle member is disposed) to lock or deter rotation of the needle member relative to the catheter body;
iii) a steering mechanism for causing the distal portion of the catheter body to become curved in the direction in which the needle member is intended to advance so as to cause the preformed curve of the needle member to mate with the induced curvature of the surrounding catheter body; and,
iv) A laterally deployable needle guide member (e.g., a balloon or rigid annular structure) that is deployable from side of the tissue penetrating catheter adjacent to the outlet opening through which the tissue penetrating member passes to support and prevent unwanted lateral xe2x80x9cplayxe2x80x9d or movement of the tissue penetrating member as it is advanced from the catheter. This outwardly deployable needle guide member is initially disposed in a xe2x80x9cstowedxe2x80x9d position wherein it does not protrude (or only minimally protrudes) from the catheter body, and is subsequently deployable to an xe2x80x9cactivexe2x80x9d position wherein it protrudes laterally from the catheter body, in the area of the needle outlet aperture, to provide support and/or guidance for the advancing tissue penetrating element (e.g., needle member or flow of energy) as the tissue penetrating element passes from the catheter body to the target location. This laterally deployable needle guide member may comprise a tubular cuff that has a lumen. The lumen of such tubular cuff may form, in combination with the catheter lumen in which the tissue penetrating element is positioned, a curvature that mates with or conforms to the preformed or intended curvature of the path of the tissue penetrating element as it passes from the catheter to the target location. In cases where the tissue penetrating element is a curved needle, the curvature of the laterally deployable needle guide member and/or catheter lumen may mate with or be the same as the curvature of the needle member.
d) Needle Member Locking Apparatus: The tissue penetrating catheter may incorporate an apparatus that prevents or deters rotation of the tissue penetration member within the catheter body prior to its advancement out of the catheter. Such rotational locking of the tissue penetrating member while it is in its retracted position serves i) to maintain the desired rotational orientation of the needle member and ii) to enhance or couple the transfer of torque from the proximal end of the catheter to the distal end of the needle, without the addition of mass or cross-sectional dimension to the catheter body.
e) Catheter Body Construction: The tissue penetrating device may comprise an elongate catheter body 12 with proximal, medial and distal segments of varying flexibility and torque strength as described more fully in U.S. patent application Ser. No. 08/837,294, incorporated herein by reference. Said catheter body may incorporate reinforcement members such as a reinforcement braid member which imparts structural integrity/stability as well as enhancing the ability of the catheter body to transmit torque along its length. In addition, it may be important for said reinforcement member to maintain the longitudinal integrity of said catheter body, and to minimize any variability of the catheter components during operation in the body.
B. Methods:
Further in accordance with the invention, there are provided methods for using the above-summarized catheter system to bypass an obstruction in a coronary artery by forming one or more arterio-venous passageways. Examples of these methods are the Percutaneous In Situ Coronary Artery Bypass (PICAB), as well as the Percutaneous Coronary Venous Arterialization (PICVA). It is understood that the same orientation steps and procedures may be used to access various targets and anatomical structures from placement of a tissue penetrating catheter within a blood vessel and orienting said catheter in accordance with this invention.
i. Percutaneous In Situ Coronary Artery Bypass (PICAB)
The PICAB procedure generally comprises the following steps:
1. Introduce a coronary sinus guide catheter into the coronary sinus;
2. Pass a tissue-penetrating catheter of the above-described type through the guide catheter and into the coronary vein;
3. Position an IVUS catheter or ultrasound transducer within the orientation structure of the tissue-penetrating catheter, and utilize the IVUS catheter or ultrasound transducer to view the artery into which the arteriovenous passageway is to extend as well as the marker that denotes the path that will be followed by the tissue penetrating member as it is advanced from the catheter body;
4. Rotate or move the tissue-penetrating catheter, as necessary, to cause the needle path indicator generated by the marker to become aligned with the lumen of the artery; and,
5. Pass the tissue penetrating element from the catheter, through the wall of the vein in which the catheter is positioned, and into the lumen of the artery, thereby forming an initial arterio-venous passageway distal to the arterial obstruction. In some embodiments, the tissue penetrating element has a lumen extending longitudinally therethrough for passage of a guidewire from vessel to vessel.
6. Move the catheter to a second location and repeat steps 4-6 to form an initial arterio-venous passageway proximal to the arterial obstruction.
7. Enlarge the proximal and distal arterio-venous passageways, if necessary, to permit the desired volume of blood flow through such passageways.
8. Place connector(s), stent(s), liner(s) or other stenting or connecting devices within the proximal and/or distal passageways, if necessary, to maintain the patency of the passageways; and,
9. Optionally, if necessary, place one or more blocker(s) within the coronary vein, or otherwise fully or partially block blood flow through the coronary vein, at location(s) that urge arterial blood to flow from the artery, through the first passageway and into the vein, through a segment of the vein, through the second passageway, and back into the artery (downstream of the blockage), thereby restoring arterial blood flow to the ischemic myocardium.
ii. Percutaneous Coronary Venous Arterialization (PICVA)
Further, in accordance with the present invention, there is provided a method for Percutaneous In Situ Coronary Venous Arterialization (PICVA) procedure, using a catheter system of the foregoing character. This preferred PICVA procedure generally comprises the steps of:
1. Introduce a coronary sinus guide catheter into the coronary sinus;
2. Pass a tissue-penetrating catheter of the above-described type through the guide catheter and into the coronary vein;
3. Position an IVUS catheter or ultrasound transducer within the orientation structure of the tissue-penetrating catheter, and utilize the IVUS catheter or ultrasound transducer to view the artery into which the arterio-venous passageway is to extend as well as the marker that denotes the path that will be followed by the tissue penetrating member as it is advanced from the catheter body;
4. Rotate or move the tissue-penetrating catheter, as necessary, to cause the needle path indicator generated by the marker to become aligned with the lumen of the artery; and,
5. Pass the tissue penetrating element from the catheter, through the wall of the vein in which the catheter is positioned, and into the lumen of the artery, thereby forming an initial arterio-venous passageway distal to the arterial obstruction.
In some embodiments, the tissue penetrating element has a lumen extending longitudinally therethrough for passage of a guidewire from vessel to vessel.
6. Enlarge the initial arterio-venous passageways, if necessary, to permit the desired volume of blood flow through such passageway.
7. Place connector(s), stent(s), liner(s) or other stenting or connecting devices within the arterio-venous passageway, if necessary, to maintain the patency of the passageway; and,
8. Optionally, if necessary, place one or more blocker(s) within the coronary vein, or otherwise fully or partially block blood flow through the coronary vein, at location(s) that urge arterial blood to flow from the artery, through the arterio-venous passageway and into the vein, such that the arterial blood will flow through the vein in a direction opposite normal venous flow, thereby retro-perfusing the ischemic myocardium by arteralization of the coronary vein.
Further aspects and advantages of the present invention will become apparent to those of skill in the art upon reading and understanding the detailed description of preferred embodiments set forth herebelow and the accompanying drawings.